During this time, Bly lived on a farm in Minnesota, with his wife and children. His first marriage was to award-winning short story novelist Carol Bly. They had four children, including Mary Bly —a best-selling novelist and Literature Professor at Fordham University as of 2011— and they divorced in 1979. Since 1980 Bly has been married to the former Ruth Counsell;[4] by that marriage he had a stepdaughter and stepson, although the stepson died in a pedestrian–train incident.

Bly's early collection of poems, Silence in the Snowy Fields, was published in 1962, and its plain, imagistic style had considerable influence on American verse of the next two decades.[5] The following year, he published "A Wrong Turning in American Poetry", an essay in which he argued that the vast majority of American poetry from 1917 to 1963 was lacking in soul and "inwardness" as a result of a focus on impersonality and an objectifying, intellectual view of the world that Bly believed was instigated by the Modernists and formed the aesthetic of most post-World War II American poetry. He criticized the influence of American-born Modernists like Eliot, Pound, Marianne Moore, and William Carlos Williams and argued that American poetry needed to model itself on the more inward-looking work of European and South American poets like Pablo Neruda, César Vallejo, Juan Ramón Jiménez, Antonio Machado, and Rainer Maria Rilke.

In 1966, Bly co-founded American Writers Against the Vietnam War and went on to lead much of the opposition to that war among writers. In 1968, he signed the “Writers and Editors War Tax Protest” pledge, vowing to refuse tax payments in protest against the war.[6] In his speech accepting the National Book Award for The Light Around the Body,[3] he announced that he would be contributing the $1000 prize to draft resistance organizations.[7] During the sixties he was of great help to the Bengali Hungryalist poets who faced anti-establishment trial at Kolkata, India. During the 1970s, he published eleven books of poetry, essays, and translations, celebrating the power of myth, Indian ecstatic poetry, meditation, and storytelling. During the 1980s he published Loving a Woman in Two Worlds,The Wingéd Life: Selected Poems and Prose of Thoreau,The Man in the Black Coat Turns, and A Little Book on the Human Shadow.

In 2006 the University of Minnesota purchased Bly's archive, which contained more than 80,000 pages of handwritten manuscripts; a journal spanning nearly 50 years; notebooks of his "morning poems"; drafts of translations; hundreds of audio and videotapes, and correspondence with many writers such as James Wright, Donald Hall and James Dickey. The archive is housed at Elmer L. Andersen Library on the University of Minnesota campus. The university paid $775,000 from school funds and private donors.

In February 2008, Bly was named Minnesota's first poet laureate.[8] In that year he also contributed a poem and an Afterword to From the Other World: Poems in Memory of James Wright. In February 2013, he was awarded the Robert Frost Medal, a lifetime achievement recognition given by the Poetry Society of America.[9]

Much of Bly's prose focuses on what he saw as a deeply troubled situation in which an increasing number of males find themselves throughout (but not limited to) today's western industrialised societies. He understood this to be a direct result of the decline in traditional fathering, which has left young boys unguided through the difficult stages of maturity. He claimed that in contrast with women who are better informed by their bodies (notably by the beginning and end of their menstrual cycle), men need to be actively guided through the path from boyhood to manhood by their elders. Pre-modern cultures had elaborate myths activated by rites of passage which helped men along this often dangerous path, as well as "men's societies" where older men would teach young boys on these gender-specific issues. He argues that this knowledge, which is as important to humans as instincts are to animals, is no longer being passed down to younger men since fathers have increasingly become absent from the household during and after the industrial revolution.[10] This "Absence of the Father" is a recurrent theme in Bly's work and many of the phenomena of depression, juvenile delinquency and lack of leadership in business and politics are linked to it.

Bly therefore sees today's men as half-adults, trapped somewhere between childhood and maturity, a state in which they find it extremely hard to become responsible leaders in their work and communities as well as fathers which eventually leads this behaviour to be passed down to the younger generations. In his book The Sibling Society (1997), Bly argues that a society formed by such men is inevitably problematic as it will also lack creativity and a deep care about others. The image of half-adults is further reinforced by popular culture which often portrays fathers as naive, often overweight and almost always emotionally co-dependent. As this is a relatively recent shift from the traditional patriarchal model, Bly believes that women rushed to fill the gap through the various youth movements during the 1960s,[11] infusing men with an enhanced emotional sensitivity which, while helping men to better understand women's age-old pain of repression, also led to the creation of "soft males" which lacked the outwardly directed strength to revitalize the community with assertiveness and a certain warrior strength.

In Bly's view, a potential solution lies in the rediscovery of the ancient meanings that are hidden in traditional myths and fairytales and are now in danger of being forgotten. He researched and collected myths that concern male maturity, many originating from the Grimms' Fairy Tales and published them in various books, Iron John being the most notable and best known example.[12] In contrast to the continual pursuit of higher achievements, that is constantly tough to young men today, the theme of spiritual descent (often being referred to by its Greek term κατάβασις) which is to be found in many of these myths, is presented as a necessary step for coming in contact with the deeper aspects of the masculine self and achieving its full potential. This is often presented as hero, often during the middle of his quest, going underground to pass a period of solitude and sorrow in semi-bestial mode. Bly notices that a cultural space existed in most traditional societies for such a period in a man's life, in the absence of which, many men today go into a depression and alcoholism as they subconsciously try to emulate this innate ritual.

Bly was influenced by the Swiss psychiatrist Carl Jung who developed the theory of archetypes, the discrete psychic structures, often perceived as mental images of human or half-human form, that exist within the human Psyche. The Powerful King, the Evil Witch and the Beautiful Maiden are, according to Jung, images imprinted in the collective unconscious of every man and Robert Bly wrote extensively about their meaning and relations to modern life. As an example and in accordance with Jung, he considered the Witch to be that part of the male psyche upon which the negative and destructive side of women is imprinted, first developed during infancy to store his own mother's imperfections. As a consequence, the Witch's symbols are essentially inverted motherly symbols, where the loving act of cooking is transformed into the brewing of evil potions and knitting clothes takes the form of spider's web. The feeding process is also reversed, with the child now in danger of being eaten to feed the body of the Witch rather than being fed by the mother's own body. In that respect, the Witch is a mark of arrested development on the part of the man as it guards against feminine realities that the his psyche is not yet able to incorporate fully. Many fairy tales describe the mostly psychic battle of incorporation in physical terms, with the hero saving his future bride by killing a witch, as in "The Drummer" (Grimms tale 193). These concepts are expounded in Bly's 1989 talk "The Human Shadow" and the book it presented.[13]